This invention relates to exhaust gas manifolds for internal combustion engines, and particularly to a specialized dual wall exhaust manifold enabling rapid temperature rise of the catalytic converter by removing minimal thermal energy from the flow of hot combustion gases from the engine, but also by exothermic combustion in the manifold itself resulting from a special, relatively simple construction.
The technology of internal combustion engines has for some years included knowledge that post engine combustion in the exhaust manifold of remaining combustible components in the exhaust gases reduces pollution from the ultimate exhaust gas discharge. Unfortunately, special manifold arrangements for accomplishing this have been technologically complex and expensive, usually involving a "nest" of hoses and/or tubes to the system, a complex louver system, or otherwise. The complexity not only involves an initial high cost, but also maintenance problems and expenses over the lifetime of the engine.